A possible new species of giant prehistoric lizard—bigger and badder than the deadly Komodo dragon—may have stalked the ancient Australian outback, a new study says.

Three fossilized bones of the mysterious 13-foot-long (4-meter-long) lizard were collected in 1966 in western Timor island.

When study leader Scott Hocknull recently examined the fossils, he was "astounded" to find that they belonged neither to the Komodo dragon—the only giant lizard species alive today—nor Megalania, a 16-foot-long (5-meter-long) extinct monster that's among the largest lizards known to have ever lived.

Giant Lizard "a Nasty Piece of Work"

The "tantalizing bones"—which date to the middle of the Pleistocene epoch (1.8 million to 11,500 years ago)—are unique enough that Hocknull suspects they represent a new species. But only "more fossils and time will tell," said Hocknull, senior curator of geosciences at Australia's Queensland Museum.

The newfound predator would have lived in open landscapes alongside giant tortoises, dwarf elephants, and perhaps even the extinct human ancestral species Homo erectus, Hocknull said.

Like the Komodo, the lizard would have ambushed its prey.

(Related: "Komodo Dragons Kill With Venom, Researchers Find.")

"Being a large terrestrial carnivore," he said, "it would have been quite a nasty piece of work."

Komodo Dragon Born in Australia?

The new analysis also notes that numerous Komodo dragon fossils at least 300,000 years old have recently been found in Australia. This is among the evidence that the animals originated, and evolved into their giant form, on the island continent, then radiated west to what is now Indonesia, the study says.

And though the new giant lizard has yet to be definitively identified as a new species, "one thing is for sure," Hocknull said: There were many more giant lizards in Australia than anybody knew.

Climate accounts for some of his certainty. Australia began to dry up about eight million years ago, creating a perfect environment for lizards, Hocknull said.

To keep up with the ever increasing sizes of their prey, prehistoric Australian lizards got beefier over time—culminating in the titanic Megalania.

But just as Australia's giant lizards were "on their way up in the evolutionary stake," they suddenly died out, Hocknull said.

No one knows how the sole survivor, the Komodo dragon, managed to scrape by in Indonesia yet disappeared in its Australian birthplace.

"Climate, or humans, or both?" Hocknull said. "The jury will remain out on this one for a while."